The figure shows a container made up of 3 sections. Cuboid D with a square base of side 14 cm and height 22 cm. Cube E with a side of 13 cm. Cuboid F that is 62 cm by 12 cm by 45 cm. Water from a tap above flows down at a rate of 2.6 litres per minute while water is drained out from the bottom at a rate of 1 litre per minute. How long did it take to fill up the container to a height of 68 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of E
= 13 x 13 x 13
= 2197 cm³ 

Volume of F
= 62 x 12 x 45
= 33480 cm³ 

1 ℓ = 1000 cm³ 
2.6 ℓ = 2600 cm³ 

Net increase in volume per minute
= 2600 - 1000
= 1600 cm³/min

Height of D to be filled with water
= 68 - (45 + 13)
= 10 cm

Volume of water in D
= 14 x 14 x 10
= 1960 cm³ 

Volume of water in F, E and part of D
= 33480 + 2197 + 1960
= 37637 cm³ 

Time taken to reach height
= 37637 ÷ 1600
≈ 24 min (Correct to nearest whole number)

Answer(s): 24 min